I went to a really religious school, so the proportion of religious studies to secular studies was astoundingly high. Even through our final years we had to take multiple Jewish studies classes covering different areas of religion, though at least they finally stopped giving us exams for them. In Year 11 I had a scripture teacher who told us that, while it was not totally obligatory, she had known people who failed biology in America because they refused to write anything about evolution on their final exams, and she thought that was admirable and we might consider it. At one stage, we were discussing marriage in a religious context, and someone raised a point about how one religious perspective/commentator or something wasn't taking into account how unhappy something might make people, I think it was about divorce and how that commentator thought you should avoid it - and she said, "It doesn't say anywhere in the bible that God wants you to be happy." She then proceeded to tell us that her grandparents had a seemingly miserable marriage and fought all the time, but THEY stayed together, and that was something worth emulating. Fortunately everyone recognised that she was an idiot, but if she'd been a primary school teacher, she could have done so. much. damage.
We also had a terrifying Chasidic philosophy teacher in years 7 and 8, who gave us a booklet of the class' topics for the year. I knew things were going to be bad when I looked down the index and found a topic on "mind control", which she proceeded to tell us was all about controlling your thoughts so as not to think about problematic things. In retrospect I think she meant not thinking about things that bother you all day, and being able to set them aside until a more convenient time to worry about them, thus assuaging anxiety. But she was exactly the sort of person who would have happily told us to use the technique to stifle religious doubt, and I think she actually did say something about quashing thoughts that were inappropriate or undesirable, so that section of classes did not go down well.
One of the very junior Jewish studies teachers really wanted to teach science, and was in the midst of training for that, so our (wonderful) science teacher (and it would not be fun teaching science in that school) let her have a go. She spent her entire lesson referring to astrology rather than astronomy.
We had an English teacher in year 12 who replaced one who left at the end of first term. She was an average teacher in terms of actual skill, but never had anything new to say about a text after the first class, and would just riff on the one theme she had picked up from every text for the rest of the time we studied it. When we were doing If This Is A Man by Primo Levi, we started a tally of the number of times she said any variation on the word "survive" in a lesson. She averaged about 40 times per double period. She also decided that reading the first text we studied during the year wasn't worth her time, even though it was going to be on our final exams.
We also had a science teacher who gave the whole class lunchtime detention because she thought we had been humming all lesson. Two people had hummed at the beginning of the lesson, and even though they had long since stopped, she kept hearing it, coming from different directions of the room, and kept getting progressively angrier, telling the class how awful this imaginary hummer was. I think she had tinnitus and didn't know it yet. This was the same person who, in year 7, called me up to the board to demonstrate a formula, checked my notebook on the way up, then told me to sit back down because she wanted someone who had gotten it wrong so she could correct them. There may well be some decent educational theory behind this, but at the time it just looked like a power trip to the class. She nearly redeemed herself by telling us that improper fractions could also be referred to as Dolly Parton fractions because they were top-heavy, but people pretty much detested her for her whole teaching style, and when she was fired kids skipped down the coridoor quietly singing "Ding Dong, The Witch Is Dead".